The present invention generally relates to improved building blocks. More particularly, the invention relates to glass blocks containing a fire-resistant gel-like substance incorporated in such a manner as to improve the aesthetics and functionality of the blocks relative to the prior art.
Glass blocks may be used instead of bricks, plaster, wood or other materials in the construction of walls and partitions. Aside from the aesthetic advantages that the glass blocks may provide over other materials, the glass blocks may be preferable because they are transparent and allow light to filter through, thereby permitting viewing through the wall, or creating a brighter room or office space.
U.S. Pat. No. 5,595,032 (incorporated herein by reference) teaches that such glass blocks may also provide improved fire resistance if the blocks are filled with certain fire-resistant gels, such as the elastomeric or gel-like product of a cured polydiorganosiloxane composition. However, the prior art is subject to several shortcomings solved by the present invention.
One disadvantage results from the prior art blocks being positioned vertically as they are filled with the fire-resistant gel. Because the gel expands when heated, the block should not be completely filled in order to maintain room for expansion of the gel within the block. If the block were completely filled, then expansion of the gel in the presence of wanner temperatures would likely cause the block to crack. The presence of this expansion area, however, leads to the undesirable result of having a line visible through the glass where the gel stops. Also, the fact that the interior faces of the block are not entirely covered with gel makes the block less effective as a fire resistor because it will take time for the faces to become covered via expansion of the gel in the presence of fire.
With the prior art blocks it also is necessary to take into account solar and other heat buildups that may expand the gel to levels that would crack the block or to levels that would not allow for sufficient expansion in the presence of fire. For this reason it is usually recommended that the blocks not be used on external walls because of the effect that direct sunlight may have on the gel.
Another disadvantage results from the need for the prior art blocks to be filled, shipped and/or installed upright and vertical. If they are tilted, or laid flat, the gel tends to peel away from the interior face of the block, leaving air bubbles or other unattractive appearances within the block.
Another disadvantage is that glass building blocks are generally large and therefore require a large quantity of gel to fill them nearly to the top. Due to reactions between this large quantity of gel and the glass, it is necessary to prime the internal surfaces of the blocks prior to insertion of the gel in order to prevent the formation of bubbles. These features not only result in an unnecessarily heavy block, but also increase its production cost.
It would be desirable, therefore, to develop a fire-resistant glass block and method for making the same that do not present the disadvantages and shortcomings discussed above.
The present invention improves upon the prior art in several ways. First, it seeks to eliminate the unsightly gel fill line by providing virtually 100% coverage of one or more of the block""s interior faces. A thickness of gel as little as five millimeters on one face has been shown to provide over thirty minutes of insulation under the British Standard 476. Therefore, the amount of gel necessary to fill the block is substantially reduced, as is the weight of the block. Furthermore, with the interior face entirely covered, the block becomes more efficient as a fire resistor because there is no time delay between the onset of fire conditions and a state of complete face coverage, as there is with the prior art blocks.
Also, the present invention may be used externally (i.e., outdoors or in partitions or walls facing outdoors) without concern about expansion of the gel from solar and other heat buildups because the gel is injected in such a way as to allow for greater expansion without damage to the glass block. Specifically, the gel is injected so that it coats one or both interior faces, thereby creating a large space for lateral expansion towards the interior of the block. It is therefore not a requirement to calculate the precise quantity of gel that can go into each block before solar expansion damage becomes a possibility.
Also, the present invention may be handled and installed in any orientation. In one preferred embodiment, the gel itself has adhesive properties that hold it to the internal faces. In another preferred embodiment, a separate adhesive may be applied to the internal surface of each face that will be coated with the gel. In either case, the gel then sticks to the face regardless of the block""s orientation.